Effects of Vitamin E and Zinc on Growth Performance, Antioxidant Status, and Innate Immunity of Grass Carp (Ctenopharyngodon idellus).

An 8-week feeding trial was conducted to investigate the effects of dietary co-supplementation vitamin E (VE) and zinc (Zn) on growth performance, antioxidant status, and immune response of juvenile grass carp (Ctenopharyngodon idellus). The experimental design consisted of seven treatments with varying combinations of dietary VE and Zn levels (mg/kg): D-0 (0:0), D-1 (0:50), D-2 (250:0), D-3 (250:50), D-4 (200:40), D-5 (150:30), and D-6 (100:20). A total of 5250 fish (average initial weight 228.11 ± 4.97 g) were randomly assigned into 21 cages (three replicates per group) and fed their respective diets twice daily for 56 days. Growth parameters, body composition, antioxidant activity, lysozyme, and complement C3 concentrations were analyzed. Significantly higher (p < 0.05) weight gain, specific growth rate, and feed efficiency were observed in the D-4 group compared to the control and singly supplemented groups. Co-supplementation also significantly enhanced serum, muscle, and liver SOD and T-AOC activities and reduced MDA concentrations. The combined supplementation of 200 mg/kg VE and 40 mg/kg Zn showed resulting in the best overall performance under the current conditions. Although the independent or interaction effects of VE and Zn were not evaluated due to the limitations of fractional factorial design, these findings not only provide a basis for improving the immune ability of grass carp by reasonably co-supplementation of VE and Zn, but also serve as a reference for reducing feeding costs in practical production.